The first phone to run on the Android OS was the HTC Dream which was launched on 22 October 2008. Google's own-brand Android phone, the HTC-made Nexus One, was launched in the US on 5 January 2010.
At present there are four main varieties of the Android OS available:
- Android 1.5 (aka 'Cupcake')
- Android 1.6 (aka 'Donut')
- Android 2.0/2.1 (aka 'Eclair')
- Android 2.2 (aka FroYo)
Each version features slightly different functionality and user interface, and recently-launched software may or may not work on older versions of the OS.
Android is an open-source operating system which means that any manufacturer can use it in their phones free of charge.